1. Field of the Invention
The present invention relates generally to medical apparatus and methods. In particular, the present invention relates to a penetration device, such as a trocar, having the ability to expand the size of a tissue penetration as the tool is advanced.
A number of endoscopic and other intraluminal procedures require penetration from one body lumen into an adjacent body lumen. For example, a number of procedures may be performed by entering the gastrointestinal (GI) tract, particularly the stomach, duodenum, small intestine and large intestine, and passing tools from the GI tract into adjacent organs, ducts, cavities and structures, such as the bile duct, the pancreatic duct, the gallbladder, urinary tract, a cyst or pseudocyst, abscess, and the like. Since the endoscopes and other endoscopic access tools are generally small with narrow working channels, typically 2 to 7 millimeters in diameter, any penetrating tools which are advanced through such working channels will necessarily be small and provide for only small tissue penetrations.
Depending on the procedure being performed, it is often desirable to place a catheter, a stent, a drainage tube, a fiducial marker implant, an electrode or a like second diagnostic or therapeutic device, through the penetrations that have been formed. Often, placement of such tools and implants requires a relatively large diameter hole to allow subsequent passage of the second device. In many cases the desired diameter of the second device is larger than the maximum diameter of the penetrating member and the insertion of the second device is often difficult. Commonly, the lumen walls include muscle layers and significant force is required to advance the catheter from one lumen to the next. Such advancement can be more difficult and may fail if the size of the penetrating element is increased in order to provide a larger penetration.
For these reasons, it would be desirable to provide trocars or other tissue-penetrating devices which can be used intraluminally to penetrate from one body lumen into an adjacent lumen where the size of the penetration can easily be enlarged. In particular, it would be desirable to provide such tools and methods where a relatively low force is needed to advance the tool through the tissue while still achieving a relatively large penetration. Such tools and methods should be compatible with standard endoscopes and other sheaths which can be used to access a target location in the gastrointestinal tract or other body lumen. At least some of these objectives will be met by the inventions described hereinbelow.
2. Description of the Background Art
Trocars and other medical access devices having deployable cutting blades are described in U.S. Pat. Nos. 5,372,588; 5,620,456; 6,402,770; 7,429,264; and US 2008/0045989. Other disclosures of interest are found in U.S. Pat. Nos. 5,224,945; 5,697,944; 6,371,964; 7,303,531; and US 2006/0190021.